If there are people hating on Kelly after this game, they really just don't have any interest in being won over by him. What more do you really expect? He wasn't drafted to be Ben Wallace.
Personally, I liked what I saw from him in the fourth quarter. Hopefully he can carry that confidence over into future games. He does seem to play better when he's on the floor with Pressey. Hopefully he can develop some chemistry with Rondo.